1. Field of the Invention
The present invention relates to a range sensor and a range image sensor.
2. Related Background Art
TOF (Time-Of-Flight) range image sensors (range sensors) have been known (see, for example, T. Y. Lee et al., “A 192×108 pixel ToF-3D image sensor with single-tap concentric-gate demodulation pixels in 0.13 μm technology,” Proceedings of the 2011 IEEE International Electron Devices Meeting, December 5-8, pp. 8.7.1-8.7.4). The range image sensor disclosed in this literature comprises a charge generating region which generates a charge in response to light incident thereon, a charge collecting region arranged on the inside of the charge generating region so as to be surrounded by the charge generating region, a charge discharging region arranged on the outside of the charge generating region so as to surround the charge generating region, an inner gate electrode which is arranged on the charge generating region and allows the charge of the charge generating region to flow into the charge collecting region in response to an input signal, and an outer discharge gate electrode which is arranged on the charge generating region and allows the charge of the charge generating region to flow into the charge discharging region in response to an input signal. The charge collecting region is arranged at a center portion of a polygonal pixel region, while the charge discharging region is arranged all around the periphery of the pixel region. An electric potential difference provided between the inner gate electrode and the outer discharge gate electrode forms a potential gradient in a region immediately below the inner gate electrode and the outer discharge gate electrode. The charge generated in the charge generating region migrates to the charge collecting region or charge discharging region according to the potential gradient.